/* SPDX-License-Identifier: GPL-2.0+ */ /* * Read-Copy Update definitions shared among RCU implementations. * * Copyright IBM Corporation, 2011 * * Author: Paul E. McKenney <[email protected]> */ #ifndef __LINUX_RCU_H #define __LINUX_RCU_H #include <linux/slab.h> #include <trace/events/rcu.h> /* * Grace-period counter management. * * The two least significant bits contain the control flags. * The most significant bits contain the grace-period sequence counter. * * When both control flags are zero, no grace period is in progress. * When either bit is non-zero, a grace period has started and is in * progress. When the grace period completes, the control flags are reset * to 0 and the grace-period sequence counter is incremented. * * However some specific RCU usages make use of custom values. * * SRCU special control values: * * SRCU_SNP_INIT_SEQ : Invalid/init value set when SRCU node * is initialized. * * SRCU_STATE_IDLE : No SRCU gp is in progress * * SRCU_STATE_SCAN1 : State set by rcu_seq_start(). Indicates * we are scanning the readers on the slot * defined as inactive (there might well * be pending readers that will use that * index, but their number is bounded). * * SRCU_STATE_SCAN2 : State set manually via rcu_seq_set_state() * Indicates we are flipping the readers * index and then scanning the readers on the * slot newly designated as inactive (again, * the number of pending readers that will use * this inactive index is bounded). * * RCU polled GP special control value: * * RCU_GET_STATE_COMPLETED : State value indicating an already-completed * polled GP has completed. This value covers * both the state and the counter of the * grace-period sequence number. */ #define RCU_SEQ_CTR_SHIFT … #define RCU_SEQ_STATE_MASK … /* Low-order bit definition for polled grace-period APIs. */ #define RCU_GET_STATE_COMPLETED … extern int sysctl_sched_rt_runtime; /* * Return the counter portion of a sequence number previously returned * by rcu_seq_snap() or rcu_seq_current(). */ static inline unsigned long rcu_seq_ctr(unsigned long s) { … } /* * Return the state portion of a sequence number previously returned * by rcu_seq_snap() or rcu_seq_current(). */ static inline int rcu_seq_state(unsigned long s) { … } /* * Set the state portion of the pointed-to sequence number. * The caller is responsible for preventing conflicting updates. */ static inline void rcu_seq_set_state(unsigned long *sp, int newstate) { … } /* Adjust sequence number for start of update-side operation. */ static inline void rcu_seq_start(unsigned long *sp) { … } /* Compute the end-of-grace-period value for the specified sequence number. */ static inline unsigned long rcu_seq_endval(unsigned long *sp) { … } /* Adjust sequence number for end of update-side operation. */ static inline void rcu_seq_end(unsigned long *sp) { … } /* * rcu_seq_snap - Take a snapshot of the update side's sequence number. * * This function returns the earliest value of the grace-period sequence number * that will indicate that a full grace period has elapsed since the current * time. Once the grace-period sequence number has reached this value, it will * be safe to invoke all callbacks that have been registered prior to the * current time. This value is the current grace-period number plus two to the * power of the number of low-order bits reserved for state, then rounded up to * the next value in which the state bits are all zero. */ static inline unsigned long rcu_seq_snap(unsigned long *sp) { … } /* Return the current value the update side's sequence number, no ordering. */ static inline unsigned long rcu_seq_current(unsigned long *sp) { … } /* * Given a snapshot from rcu_seq_snap(), determine whether or not the * corresponding update-side operation has started. */ static inline bool rcu_seq_started(unsigned long *sp, unsigned long s) { … } /* * Given a snapshot from rcu_seq_snap(), determine whether or not a * full update-side operation has occurred. */ static inline bool rcu_seq_done(unsigned long *sp, unsigned long s) { … } /* * Given a snapshot from rcu_seq_snap(), determine whether or not a * full update-side operation has occurred, but do not allow the * (ULONG_MAX / 2) safety-factor/guard-band. */ static inline bool rcu_seq_done_exact(unsigned long *sp, unsigned long s) { … } /* * Has a grace period completed since the time the old gp_seq was collected? */ static inline bool rcu_seq_completed_gp(unsigned long old, unsigned long new) { … } /* * Has a grace period started since the time the old gp_seq was collected? */ static inline bool rcu_seq_new_gp(unsigned long old, unsigned long new) { … } /* * Roughly how many full grace periods have elapsed between the collection * of the two specified grace periods? */ static inline unsigned long rcu_seq_diff(unsigned long new, unsigned long old) { … } /* * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally * by call_rcu() and rcu callback execution, and are therefore not part * of the RCU API. These are in rcupdate.h because they are used by all * RCU implementations. */ #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD #define STATE_RCU_HEAD_READY … #define STATE_RCU_HEAD_QUEUED … extern const struct debug_obj_descr rcuhead_debug_descr; static inline int debug_rcu_head_queue(struct rcu_head *head) { … } static inline void debug_rcu_head_unqueue(struct rcu_head *head) { … } #else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ static inline int debug_rcu_head_queue(struct rcu_head *head) { return 0; } static inline void debug_rcu_head_unqueue(struct rcu_head *head) { } #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ static inline void debug_rcu_head_callback(struct rcu_head *rhp) { … } extern int rcu_cpu_stall_suppress_at_boot; static inline bool rcu_stall_is_suppressed_at_boot(void) { … } extern int rcu_cpu_stall_notifiers; #ifdef CONFIG_RCU_STALL_COMMON extern int rcu_cpu_stall_ftrace_dump; extern int rcu_cpu_stall_suppress; extern int rcu_cpu_stall_timeout; extern int rcu_exp_cpu_stall_timeout; extern int rcu_cpu_stall_cputime; extern bool rcu_exp_stall_task_details __read_mostly; int rcu_jiffies_till_stall_check(void); int rcu_exp_jiffies_till_stall_check(void); static inline bool rcu_stall_is_suppressed(void) { … } #define rcu_ftrace_dump_stall_suppress() … #define rcu_ftrace_dump_stall_unsuppress() … #else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */ static inline bool rcu_stall_is_suppressed(void) { return rcu_stall_is_suppressed_at_boot(); } #define rcu_ftrace_dump_stall_suppress … #define rcu_ftrace_dump_stall_unsuppress … #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ /* * Strings used in tracepoints need to be exported via the * tracing system such that tools like perf and trace-cmd can * translate the string address pointers to actual text. */ #define TPS(x) … /* * Dump the ftrace buffer, but only one time per callsite per boot. */ #define rcu_ftrace_dump(oops_dump_mode) … void rcu_early_boot_tests(void); void rcu_test_sync_prims(void); /* * This function really isn't for public consumption, but RCU is special in * that context switches can allow the state machine to make progress. */ extern void resched_cpu(int cpu); #if !defined(CONFIG_TINY_RCU) #include <linux/rcu_node_tree.h> extern int rcu_num_lvls; extern int num_rcu_lvl[]; extern int rcu_num_nodes; static bool rcu_fanout_exact; static int rcu_fanout_leaf; /* * Compute the per-level fanout, either using the exact fanout specified * or balancing the tree, depending on the rcu_fanout_exact boot parameter. */ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) { … } extern void rcu_init_geometry(void); /* Returns a pointer to the first leaf rcu_node structure. */ #define rcu_first_leaf_node() … /* Is this rcu_node a leaf? */ #define rcu_is_leaf_node(rnp) … /* Is this rcu_node the last leaf? */ #define rcu_is_last_leaf_node(rnp) … /* * Do a full breadth-first scan of the {s,}rcu_node structures for the * specified state structure (for SRCU) or the only rcu_state structure * (for RCU). */ #define _rcu_for_each_node_breadth_first(sp, rnp) … #define rcu_for_each_node_breadth_first(rnp) … #define srcu_for_each_node_breadth_first(ssp, rnp) … /* * Scan the leaves of the rcu_node hierarchy for the rcu_state structure. * Note that if there is a singleton rcu_node tree with but one rcu_node * structure, this loop -will- visit the rcu_node structure. It is still * a leaf node, even if it is also the root node. */ #define rcu_for_each_leaf_node(rnp) … /* * Iterate over all possible CPUs in a leaf RCU node. */ #define for_each_leaf_node_possible_cpu(rnp, cpu) … /* * Iterate over all CPUs in a leaf RCU node's specified mask. */ #define rcu_find_next_bit(rnp, cpu, mask) … #define for_each_leaf_node_cpu_mask(rnp, cpu, mask) … #endif /* !defined(CONFIG_TINY_RCU) */ #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_TASKS_RCU_GENERIC) /* * Wrappers for the rcu_node::lock acquire and release. * * Because the rcu_nodes form a tree, the tree traversal locking will observe * different lock values, this in turn means that an UNLOCK of one level * followed by a LOCK of another level does not imply a full memory barrier; * and most importantly transitivity is lost. * * In order to restore full ordering between tree levels, augment the regular * lock acquire functions with smp_mb__after_unlock_lock(). * * As ->lock of struct rcu_node is a __private field, therefore one should use * these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock. */ #define raw_spin_lock_rcu_node(p) … #define raw_spin_unlock_rcu_node(p) … #define raw_spin_lock_irq_rcu_node(p) … #define raw_spin_unlock_irq_rcu_node(p) … #define raw_spin_lock_irqsave_rcu_node(p, flags) … #define raw_spin_unlock_irqrestore_rcu_node(p, flags) … #define raw_spin_trylock_rcu_node(p) … #define raw_lockdep_assert_held_rcu_node(p) … #endif // #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_TASKS_RCU_GENERIC) #ifdef CONFIG_TINY_RCU /* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */ static inline bool rcu_gp_is_normal(void) { return true; } static inline bool rcu_gp_is_expedited(void) { return false; } static inline bool rcu_async_should_hurry(void) { return false; } static inline void rcu_expedite_gp(void) { } static inline void rcu_unexpedite_gp(void) { } static inline void rcu_async_hurry(void) { } static inline void rcu_async_relax(void) { } static inline bool rcu_cpu_online(int cpu) { return true; } #else /* #ifdef CONFIG_TINY_RCU */ bool rcu_gp_is_normal(void); /* Internal RCU use. */ bool rcu_gp_is_expedited(void); /* Internal RCU use. */ bool rcu_async_should_hurry(void); /* Internal RCU use. */ void rcu_expedite_gp(void); void rcu_unexpedite_gp(void); void rcu_async_hurry(void); void rcu_async_relax(void); void rcupdate_announce_bootup_oddness(void); bool rcu_cpu_online(int cpu); #ifdef CONFIG_TASKS_RCU_GENERIC void show_rcu_tasks_gp_kthreads(void); #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */ static inline void show_rcu_tasks_gp_kthreads(void) {} #endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */ #endif /* #else #ifdef CONFIG_TINY_RCU */ #ifdef CONFIG_TASKS_RCU struct task_struct *get_rcu_tasks_gp_kthread(void); void rcu_tasks_get_gp_data(int *flags, unsigned long *gp_seq); #endif // # ifdef CONFIG_TASKS_RCU #ifdef CONFIG_TASKS_RUDE_RCU struct task_struct *get_rcu_tasks_rude_gp_kthread(void); void rcu_tasks_rude_get_gp_data(int *flags, unsigned long *gp_seq); #endif // # ifdef CONFIG_TASKS_RUDE_RCU #ifdef CONFIG_TASKS_TRACE_RCU void rcu_tasks_trace_get_gp_data(int *flags, unsigned long *gp_seq); #endif #ifdef CONFIG_TASKS_RCU_GENERIC void tasks_cblist_init_generic(void); #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */ static inline void tasks_cblist_init_generic(void) { } #endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */ #define RCU_SCHEDULER_INACTIVE … #define RCU_SCHEDULER_INIT … #define RCU_SCHEDULER_RUNNING … enum rcutorture_type { … }; #if defined(CONFIG_RCU_LAZY) unsigned long rcu_get_jiffies_lazy_flush(void); void rcu_set_jiffies_lazy_flush(unsigned long j); #else static inline unsigned long rcu_get_jiffies_lazy_flush(void) { return 0; } static inline void rcu_set_jiffies_lazy_flush(unsigned long j) { } #endif #if defined(CONFIG_TREE_RCU) void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq); void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, unsigned long secs, unsigned long c_old, unsigned long c); void rcu_gp_set_torture_wait(int duration); #else static inline void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq) { *flags = 0; *gp_seq = 0; } #ifdef CONFIG_RCU_TRACE void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, unsigned long secs, unsigned long c_old, unsigned long c); #else #define do_trace_rcu_torture_read … #endif static inline void rcu_gp_set_torture_wait(int duration) { } #endif #ifdef CONFIG_TINY_SRCU static inline void srcutorture_get_gp_data(struct srcu_struct *sp, int *flags, unsigned long *gp_seq) { *flags = 0; *gp_seq = sp->srcu_idx; } #elif defined(CONFIG_TREE_SRCU) void srcutorture_get_gp_data(struct srcu_struct *sp, int *flags, unsigned long *gp_seq); #endif #ifdef CONFIG_TINY_RCU static inline bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) { return false; } static inline unsigned long rcu_get_gp_seq(void) { return 0; } static inline unsigned long rcu_exp_batches_completed(void) { return 0; } static inline unsigned long srcu_batches_completed(struct srcu_struct *sp) { return 0; } static inline void rcu_force_quiescent_state(void) { } static inline bool rcu_check_boost_fail(unsigned long gp_state, int *cpup) { return true; } static inline void show_rcu_gp_kthreads(void) { } static inline int rcu_get_gp_kthreads_prio(void) { return 0; } static inline void rcu_fwd_progress_check(unsigned long j) { } static inline void rcu_gp_slow_register(atomic_t *rgssp) { } static inline void rcu_gp_slow_unregister(atomic_t *rgssp) { } #else /* #ifdef CONFIG_TINY_RCU */ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp); unsigned long rcu_get_gp_seq(void); unsigned long rcu_exp_batches_completed(void); unsigned long srcu_batches_completed(struct srcu_struct *sp); bool rcu_check_boost_fail(unsigned long gp_state, int *cpup); void show_rcu_gp_kthreads(void); int rcu_get_gp_kthreads_prio(void); void rcu_fwd_progress_check(unsigned long j); void rcu_force_quiescent_state(void); extern struct workqueue_struct *rcu_gp_wq; extern struct kthread_worker *rcu_exp_gp_kworker; void rcu_gp_slow_register(atomic_t *rgssp); void rcu_gp_slow_unregister(atomic_t *rgssp); #endif /* #else #ifdef CONFIG_TINY_RCU */ #ifdef CONFIG_RCU_NOCB_CPU void rcu_bind_current_to_nocb(void); #else static inline void rcu_bind_current_to_nocb(void) { } #endif #if !defined(CONFIG_TINY_RCU) && defined(CONFIG_TASKS_RCU) void show_rcu_tasks_classic_gp_kthread(void); #else static inline void show_rcu_tasks_classic_gp_kthread(void) {} #endif #if !defined(CONFIG_TINY_RCU) && defined(CONFIG_TASKS_RUDE_RCU) void show_rcu_tasks_rude_gp_kthread(void); #else static inline void show_rcu_tasks_rude_gp_kthread(void) {} #endif #if !defined(CONFIG_TINY_RCU) && defined(CONFIG_TASKS_TRACE_RCU) void show_rcu_tasks_trace_gp_kthread(void); #else static inline void show_rcu_tasks_trace_gp_kthread(void) {} #endif #ifdef CONFIG_TINY_RCU static inline bool rcu_cpu_beenfullyonline(int cpu) { return true; } #else bool rcu_cpu_beenfullyonline(int cpu); #endif #if defined(CONFIG_RCU_STALL_COMMON) && defined(CONFIG_RCU_CPU_STALL_NOTIFIER) int rcu_stall_notifier_call_chain(unsigned long val, void *v); #else // #if defined(CONFIG_RCU_STALL_COMMON) && defined(CONFIG_RCU_CPU_STALL_NOTIFIER) static inline int rcu_stall_notifier_call_chain(unsigned long val, void *v) { return NOTIFY_DONE; } #endif // #else // #if defined(CONFIG_RCU_STALL_COMMON) && defined(CONFIG_RCU_CPU_STALL_NOTIFIER) #endif /* __LINUX_RCU_H */
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